1. Field of the Invention
The present invention relates to a security control system. Illustrative embodiments of the invention relate to a security system comprising video cameras, the control system, and monitors for displaying images received by the cameras.
2. Description of the Prior Art
Security CCTV systems are now finding widespread use in monitoring shopping centres, town centres, and commercial and industrial buildings.
The size of these systems may vary from one or two video sources for small retail outlets, petrol stations etc., to large town centre installations which may have greater than a hundred video sources with hundreds of alarm input signals.
In large installations, a great deal of security information is provided to the operators for evaluation. Such large security systems are typically managed by a system controller which can: provide access to a large number of video sources (for example, a hundred video sources) and many hundreds of alarm signals; allow control of pan and tilt heads for each camera; provide some control panels (e.g. ten or fewer control panels) for enabling an operator to interact with the system and present video information on some (e.g. thirty or more) video monitors.
Managing this information to ensure that any incident may be efficiently and effectively identified, dealt with and recorded for evidential purposes can be very operator intensive.
To improve the efficiency of the monitoring process, large security sites are often partitioned or broken down into areas, with one operator assigned responsibility for monitoring each area.
System controllers may provide the facilities to effectively partition an installation into a number, for example eight, fully functioning sub-systems. Each sub-system has a control interface, a number of video monitors, and access to a sub-set of the video sources and alarm information from the complete installation.
The monitors are watched by operators who use the control panels, e.g. in response to alarms, to control the views presented by the cameras in order to determine the cause of an alarm. Even by assigning one operator to each partition of an installation, an event may trigger many alarms and present the operator with an overwhelming amount of alarm and video information.
Consider by way of example a CCTV security system having 128 camera and 32 video display monitors.
The problem with such a large number of cameras and video display monitors is that it becomes very difficult for security operators to effectively monitor all of the video information provided.
It is possible to reduce the number of monitors. For example 16 monitors could each show a fixed sequence of eight cameras giving full coverage of all video information in the system. A fine balance must however be reached between the number of video monitors and the number of steps in the camera sequence. For example, if each camera in a sequence of eight cameras is displayed for three seconds, then there will be a 24-second (eight source multiplied by three seconds) delay until the sequence is complete. This delay may be unacceptable for effective monitoring and important information could be missed.
It is possible to use 32 monitors each displaying four one-quarter size images to ensure that all 128 video signals are displayed. In this installation there is no time delay as four images are displayed on each video monitor simultaneously. Again however the number of video displays can be a problem for effective monitoring purposes, and the system installation becomes expensive to purchase, manage and maintain due to the large amounts of equipment required.
The number of monitors required could be reduced if multi-picture display devices capable of producing nine or 16 images were used. The problem with this approach is that the individual images become very small and it can be difficult to derive sufficient detail from the images for effective monitoring. The installation of these devices is also inflexible in that the order or combination of images displayed on each monitor cannot be easily changed. Although all 128 camera images are displayed, the number and combination of images on each display device may be non-optimum for effective monitor purposes.
Embodiments of the present invention seek to provide a security system in which a reduced number of monitors allow effective surveillance of images from a large number of cameras.
According to one aspect of the present invention there is provided a control system for use with a surveillance system having n cameras for producing video signals representing images viewed by the cameras and p display devices for displaying the said images where n is greater than p, the control system comprising video switching means having n inputs for receiving respective video signals from the cameras, and p outputs, the switching means being able to selectively connect any one of the n inputs to any one of the p outputs, p display control means able to apply selectable scaling and positioning to video signals received from the outputs to display, simultaneously on a display, one or more selectively scaled and positioned images, and control means for controlling the video switching means and the display control means to select the video signals applied to each display control means, the sequence in time in which the selected video signals are applied, and to select the scaling and positioning of the selected video signals for display.
According to another aspect of the present invention there is provided a control system comprising first video switching means having n inputs for receiving respective video signals and m outputs any one or more of the n inputs being connectable to any one or more of m outputs where m is less than n display control means for selectively coupling the m outputs to p display devices where p is less than m, the display control means being operable to selectively scale the images represented by the video and to selectively position the scaled images on the p display devices, and programmable control means for selecting and varying the selection of the connections of the said inputs of the switching means to the said outputs of the switching means and for selecting and varying the sequence in time in which the said connections are established, and for selecting and varying the scaling and positioning of the images by the display control means.
Thus the present invention avoids the difficult discussed above by combining the ability to display sets of one or more pictures on a display device with the ability to vary the sequences of pictures displayed.
A preferred embodiment of the invention combines multi-picture displays with a sequence program function.
In an embodiment of the invention, the display control means comprises p channels, each channel being connected to m/p outputs of the switching means, and being operable to scale and position any one or more of m/p images on one display device. An example of a channel comprises image scaling means, a multiplexer controlled by the programmable control means for selectively connecting any one of the m/p outputs to the image scaling means, and means for forming a video signal representing one or more scaled images in selected display positions, the scaling means and forming means being controlled by the programmable control means.
This allows a display device connected to one channel to display images in various sizes e.g. full size, xc2xc size, {fraction (1/9)} size and in different positions e.g. picture-in-picture, or an array of four or eight pictures. Furthermore because the switching means is able to connect any input to any output and in any sequence (under the control of the programmable control means) and the multiplexer is also able to connect any one of its inputs to the imaging scaling means in any sequence any combination of one to m/p cameras can be assigned to any one of the display devices for display in any one of many different display formats, and in any one of many different sequences
The programmable control means may store a plurality of different display formats, e.g. combinations of one or more images as picture in picture displays or arrays with predetermined scaling and positioning of the images, for retrieval and use. Preferably, in addition, predetermined sequences of formats are stored for retrieval and use.
In a preferred embodiment of the invention the programmable control mans comprises a first programmable controller associated with the video switching means and operable to control the selection of the connections of the said inputs of the switching means to the said outputs thereof and/or the said sequence in time; and a second programmable controller which cooperates with the first programmable controller and associated with the display control means for controlling at least the scaling and positioning of the said images on the p display devices. Thus control of the connections and sequences in the switching means is conveniently separated from control of scaling and display formats in the display control means. The second programmable controller preferably controls the multiplexer of the channel to control the selection of the m/p outputs of the switching means which are coupled to the scaling means. Thus further control of the selection and sequencing of images is provided in the display control means.
Preferably, the second programmable controller includes program storage means for storing a plurality of different display formats, each display format comprising a combination of image display sizes, image display positions for the images represented by video signals received from the m/p outputs of the switching means and/or image sequences. The stored image scales may include full size, and a plurality of different fractional sizes. The fractional sizes may include quarter size and one ninth size. The stored display formats may include picture-in-picture displays and different arrays of separate images simultaneously displayed. The arrays may include an array of four images and an array of eight images.
Thus many different single and multi-picture screen formats and sequences may be stored in the controller of the display control means and recalled for use as necessary.
The above, and other objects, features and advantages of this invention will be apparent from the following detailed description of illustrative embodiments which is to be read in connection with the accompanying drawings.